MM cartridges and capacitance

Perhaps a naive question:

If "higher than standard 47k" capacitance was known to optimize frequency response by an MM cart's designers, wouldn't they have included that higher capacitance value in the spec sheet for that cart?

I use MMs almost exclusively and find these discussions most informative, though I've no simple and reliable means to increase the capacitance loading via my MM phono stage.

T_bone & Lew, thanks very much for the nice words.

JB, in my experience MM cartridge specs do usually indicate recommended load capacitance.

The 47K number, btw, is not capacitance, it is the recommended load RESISTANCE (47,000 ohms) for many MM's, and approximately corresponds to the input resistance of many or most phono stages or preamp phono inputs, that are intended for use with MM's.

Recommended load capacitance for MM's is typically in the area of 100 to 400 pf (picofarads). The cabling will usually be a more significant contributor to that than the input capacitance of the phono stage or preamp phono input, if the phono stage or preamp does not have a provision to switch in additional capacitance.

As you may realize, capacitance can be added by soldering an appropriate capacitor to an rca plug, and connecting it at the phono stage or preamp phono input with a y-adapter. I have a commercially made kit that I purchased in the 1980's which provides a selection of rca plugs with capacitors of various values soldered onto them, but I haven't seen such a kit offered in recent times.

Best regards,
-- Al

DB systems apparently still makes the kit that they offered in the 80s, I just sold my old one. It was mentioned in Stereophile in the last year or so. I think it is $69.95, not a bad price considering it was $39.95 then. DB is a good company but one of the stealth variety, I had no idea that they were still going.

Here is their address; I was a dealer for them years ago but have had no connection for over 20 years.

DB Systems
PO BOX 460
214 Main Street
Rindge, NH 03461
- USA -
Email UsEmail Us

phone: (603) 899-5121

Established in 1975, DB Systems is a manufacturer of high quality home audio equipment, including preamps, power amps, electronic crossovers, tone control, head amp, phase inverter, and accessories. We also sell test CDs. We take Mastercard, VISA, Discover and Paypal.
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Thanks, Stan. I just checked and sure enough my "Phono Equalization Kit" was made by DB Systems.

It provides polystyrene capacitors, mounted on rca plugs, with values of 100, 150, 200, 300, and 400 pf; 100 ohm 1% metal film resistors mounted on rca plugs for use with MC's; a pair of spare plugs; and a pair of y-adapters. The part number of the kit was DBP-6.

The instructions also made reference to a DBP-11 "Capacitance Loading Switchbox," which could accept inputs from two turntables, provide independently selectable capacitive loading of each cartridge, and allow the user to select which cartridge's outputs are routed to the phono stage.

Best regards,
-- Al